1. Field of the Invention
The present invention relates to a speaker, and more particularly, to a damper of a rectangular-shaped slim speaker that is capable of preventing a vibration plate having an entire outer appearance of a slim oval/track-like shape extended to any one side thereof from being moved in forward and backward directions.
2. Background of the Related Art
According to a general speaker structure, current of a power amplifier flows through the voice coil wound around a voice coil former of a speaker unit, and at which time the flowing current generates a magnetic field expanding and contracting at the same frequency as the audio signal around the voice coil. In this case, since the voice coil is caught in the magnetic field generated by the magnet in the speaker unit, the voice coil former having the voice coil wound therearound is moved in forward and backward directions by means of the cooperative actions with the magnetic field generated from the voice coil to correspond to the generated magnetic field.
At this time, as the voice coil former has been coupled to a vibration plate, the vibration plate pushes air while being moved in the forward and backward directions together with the voice coil former, thereby generating sound due to the vibration of the air. In this case, if the vibration is generated unstably, the generated sound may be broken up or distorted. To prevent such problems from occurring in the speaker, thus, the voice coil former having the voice coil that serves to move the vibration plate in the forward and backward directions is connected to the speaker unit by means of a damper, so as to control the width of the vibration of the vibration plate.
If the vibration plate is formed in a round shape, however, the damper also has a round shape such that the amplitudes of the vibration plate can be uniformly maintained, thereby stably controlling the width of the vibration. Contrarily, if the vibration plate is formed in a slim rectangular shape, as shown in FIG. 5, the voice coil former connected with the vibration plate also has the slim rectangular shape, and even the damper also has the slim rectangular shape. Such a rectangular-shaped damper has the front and back widths larger than the left and right widths thereof, such that there occurs a defect that the width of the vibration is not uniformly generated.
To overcome the defect occurring in the rectangular shape of damper, recently, there has been proposed another type of conventional damper of the rectangular-shaped slim speaker, as shown in FIG. 6, wherein a plastic film or sheet having a given strength corresponding to the vibration of the vibration plate is forcedly bent and fixed to the both end portions of the rectangular voice coil former and the speaker unit, thereby making the width of vibration of the rectangular voice coil former stably maintained. However, in case where the damper is molded to a shape of plastic film or sheet, it does not have uniform thickness or smoothness, such that it cannot maintain the upper and lower amplitudes uniformly in response to the vibration of the vibration plate, thereby causing the distortion of the sound generated from the vibration plate. Furthermore, the plastic film or sheet has a force of returning to its original shape from its forced-bending state, thereby making it difficult to uniformly maintain the upper and lower amplitudes of the vibration plate, and additionally, the elasticity of the plastic film or sheet is decreased according to the repeated use. Thus, the upper and lower amplitudes of the vibration plate are not moved in a vertical direction, but moved in left and right directions, such that undesirably, the distortion of the sound occurs.